import java.awt.*;
import java.util.Scanner;

public class JavaSETest {
    public static String orderOutput (String s) {
        int[] chars = new int[200];
        for (char i = 'a'; i <= 'Z'; i++) {
            chars[i] = 1;
        }
        int j = 0;
        StringBuilder stringBuilder = new StringBuilder();
        while (j < s.length()) {
            char k = s.charAt(j);
            if (chars[k] != 0) {
                chars[k] = 0;
                j++;
                stringBuilder.append(k);
            } else {
                break;
            }
        }
        return stringBuilder.toString();
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = null;
        while (in.hasNextLine()) {
            s = in.nextLine();
            String ret = orderOutput(s);
            System.out.println(ret);
        }
    }

    class ListNode {
        int val;
        ListNode next = null;
        public ListNode (int val) {
            this.val = val;
        }
        public ListNode(){};
    }

    public ListNode Merge (ListNode pHead1, ListNode pHead2) {
        ListNode ret = new ListNode();
        ret = pHead1;
        if (pHead1.val < pHead2.val) {
            ret = pHead1;
        } else {
            ret = pHead2;
        }
        while (pHead1 != null && pHead2 != null) {
            if (pHead1.val < pHead2.val) {
                ret.next = pHead1;
                pHead1 = pHead1.next;
            } else {
                ret.next = pHead2;
                pHead2 = pHead2.next;
            }
        }
        if (pHead1 == null) {
            ret.next = pHead2;
        } else {
            ret.next = pHead1;
        }
        return ret;
    }
}
